Discharge tube or the like



' Sept. 26, 1939.

w. L. KRAHL 2,1 73,880 DISGKARGE TUBE OR THE LIKE Filed April 19, 1934 INVENTOR ATTORNEY Patented Sept. 26, 1939 DISCHARGE TUBE OR- THE LIKE Walter Louis Krahl, Swampscott, Mass, assignor to Hygrade Sylvania. Corporation, Salem, Mass, a corporation of Massachusetts Application April 19,

12 Claims.

This invention relates to electric discharge devices and with particularity to devices generally referred to as radio tubes, vacuum tubes, or the like.

An object of the invention is to provide novel means for supporting the electrode assembly of an electron discharge tube or the like.

Another object is to provide a novel device for resiliently supporting an electrode assembly interiorly against the wall of an enclosing envelope or the like.

In radio tubes generally, and more especially in the modern types of tubes, it is imperative that the various electrodes of the electrode assembly be maintained accurately in predetermined spatial relations, both with respect toone another and also with respect to the wall of the enclosing envelope. The necessity for maintaining the electrodes in fixed relation to the envelope is occasioned by the undesirable effects of changes in capacitance between the electrodes of the tubes and surrounding shields or other conductors. Furthermore, it is often impracticable to secure the elements of tubes in fixed relation to one another by interposing an insulating spacer between them and it is more convenient to minimize relative motion between the electrodes by supporting, those elements which are most inclined to move, against the inner walls of the envelopes. Supporting the end of the structure further from the press by bracing it against the envelope, minimizes the tendency for the supporting wires to be bent or the glass adjacent these wires to be cracked when the tube is submitted to severe shock. If the means for supporting the electrodes against the envelope are non-resilient, the normal variations in the dimensions of the envelopes will result in small clearance between the supports and the larger envelopes and annoying rattles due to intermittent collision between the supports and the envelopes will be occasioned by sound waves or other vigrations. The supports bearing against the envelope should therefore be flexible, but must be sufiiciently rigid to prevent motion of the electrodes when subjected to normal vibration which would otherwise result in microphonic disturbances in the output of the tube when the latter is in use.

Accordingly, one of the principal objects of this invention is to provide a radio tube, lamp or similar device, wherein the filament or electrode assembly is supported both from the press as well as from the upper end of the envelope, whereby variations in the characteristics of the tube are substantially prevented even when the tube is subjected to heavy jars or vibrations.

Another object of the invention is to provide a so-called single-press tube with means for supporting the electrode assembly against tilting movement with respect to the press, without at 1934, Serial No. 721,286

the same time materially increasing the assembly cost or assembly time.

A feature of the invention relates to a radio tube of the so-callcd dome envelope type in conjunction with a novel form of resilient spacer.

There is disclosedin Patent No. 2,111,002, a resilient spacer consisting of a specially shaped strip of mica or other resiliently deformable material, which is self-locked to the electrode assembly. As disclosed in said application, the mica spacer member is adapted to engage the inner wall of a radio tube in such a way that the strip tends to conform itself to the curvature of said wall. Thus in the case of tubes having cylindrical domes, the spacer strip or strips tend to assume the shape of a cylindrical sector, with the vertical edge portions of the strip substantially parallel the axis of the tube. In certain instances, the use of spacers such as disclosed in said application, renders comparatively difficult the assembling of the electrode unit in the bulb, since the vertical lateral edge portions of the spacer strips must conform to the curvature of the tube wall, and the relative movement between the envelope and electrode unit must be parallel to the vertical axis of the tube.

Accordingly, another feature of the present invention relates to a resilient spacer which provides the necessary resilient support to the electrode unit, and one which more readily adapts: itself to tube envelopes of different shapes and sizes. In carrying out this feature of the invention, there is preferably employed a strip of resiliently deformable material such as mica or the like, which is interlocked with the electrode assembly in such a manner that it is capable of tilting movement with respect to the vertical axis of the tube, so that the strip does not have to conform itself to the curved contour of the tube Wall.

Other features and advantages not specifically enumerated will be apparent after a consideration of the following detailed description and the appended claims.

W'hile the invention will be disclosed herein as embodied in specific forms, it will be understood that the invention is not limited thereto, but is capable of embodiment in tubes, lamps, and similar devices of different shapes and sizes.

Accordingly in the drawing, Figure 1 is an elevational view, partly in section, of a typical form of radio tube embodying features of the invention. Figure 2 is a top plan view of Figure l, with the resilient spacers removed. Figure 3 is a top plan view of Figure 1, showing the resilient spacers in position. Figure 4 is a detailed side view of Figure 1 with one of the resilient spacers removed. Figure 5 is an enlarged detailed view of one of the resilient spacers according to the invention. Figure 6 shows a modified manner of end in a substantially cylindrical dome portion 5.

The electrode assembly is indicated generally in Figure 1 by the numeral 5, and this assembly may take any well known form. Merely for purposes of illustration, there is shown in Figure 4 a detailed electrode assembly such as is employed in so-called full-wave rectifier devices. As shown in Figure 4, the electrode assembly comprises a pair of anodes 1 and 8. Each anode, for example anode 1, may consist of a pair of metal plates 9, l3, each plate having a semi-circular depression extending longitudinally thereof to define a hollow cylindrical discharge space when the plates 9 and ID are assembled as shown. Sealed into the press 4 are a pair of metal rods or wires H and I2. The anode 1 is fastened, for example by spot welding, to the rod II, and in like manner the anode 8 is fastened to the rod l2. The plates 9 and Ill of anode 1 are also spot welded to a rod I3, and a similar rod I4 is spot welded to the plates of anode 8. Sealed into the press 4 are two sets of wires, l5, l6, l1 and I8, I9, 25. Supported by the wire [1 is a metal tube or sleeve 2! which has its exterior surface provided with a coating or coatings of electron emissive material such as ordinarily employed in socalled indirectly heated cathodes. Insulatingly supported within the sleeve 2| is a heater wire or filament 22, which has its ends connected respectively to the wires 15 and I6. Similarly, the Wire 20, supports a cathode sleeve 23, which is provided with a filament or heater 24, the ends of which are connected to wires l8 and IS. The double electrode assembly above described is interlocked as a suit by means of an upper insulator disc 25 and a lower insulator disc 25. As shown in detail in Figures 2 and 3, the disc 25 is provided with perforations 21, 28, 29, 30 to receive the upper ends of the wire l3, l4 and 2 respectively. The disc 25 is also provided with a pair of perforations 3|, 32, to receive the upper ends of the cathode sleeves 2| and 23. It will be understood, of course, that the lower disc 26 is provided with perforations similar to those provided in disc 25. For the purpose of rigidly interlocking the discs 25 and 26 to the electrode assembly, each disc is provided with two pairs of openings 33, 34, 35, 35. Each disc is also provided with a pair of substantially T-shaped metal straps 31, 38, these straps being in turn welded or otherwise fastened to the anodes 1 and 8 as shown more clearly in Figure 4 of the drawing. By means of the discs 25, 25 and the metal straps 31, 38, 39, 48, all the component parts of the electrode assembly are interlocked as a unit and relative movement between the electrodes is eliminated.

Preferably the above described electrode assembly or unit is supported from the press 4 at such a distance that the upper disc 25 is within the dome portion of the tube envelope. In order to prevent excessive vibration of the electrode assembly with relation tothe press 4, there are provided, as shown in Figures 1, 3 and 4, a pair of resilient spacer members indicated generally by the numerals 39, 40. Each of the spacer members is in general E-shaped, comprising a pair of parallel side portions 4|, 42 and a central portion 43, joined by a yoke portion 44. The yoke 44 is undercut at 45, 46 to allow the side portions 4| and 42 to be flexed with respect to the portion 43. a Portion 43 is provided with looking shoulders 41, 48, and likewise portions 4| and 42 are provided with looking shoulders 49 and 53. For the purpose of locking each spacer member in position, the disc 25 (Fig. 2) is provided with a pair of slots 5|, 52, and the edge of said disc 25 is also provided with notches 53, 54 and 55, 56. The slot 5| for example, is adapted to receive the central portion 43 of a spacer member, while the notches 53 and 54 are adapted to receive the portions 4| and 42 of this same spacer member. It will be noted that the slot 5| is off-set with respect to notches 53 and 54, so that when the spacer member is assembled in position, the central portion 43 is substantially vertical While the lateral portions 4| and 42 are inclined, as shown more clearly in Figs. 1 and 3. It will be noted that slot 5| is provided with corners or shoulders 51, 58 to lock the spacer member against upward movement. Likewise the inner ends of notches 53 and 54 are adapted to engage the shoulders 49 and 50 to lock the spacer member against downward movement. As hereinabove stated, the spacer members are preferably of sheet mica or other similar flexible insulating material, so that when the portion 43 is inserted in slot 5|, and portions 4| and 42 are inserted in notches 53 and 54, the springy character of the material forces the shoulders 41 and 48 into looking engagement with shoulders 51 and 58.

Preferably, the spacer members are so proportioned that the portions 4| and 42 project downwardly a'suificient distance below the disc 25, to engage the shoulder 59 of the bulb This engagement may cause a very slight bending of the spacer portions 4| and 42 as shown in exaggerated form by the dotted lines (Fig. 1). It is to be noted, therefore, that because of the notches 53 and 54, the portions 4| and 42 of the spacer member, do not conform themselves in any way to the curved contour of the bulbbut merely flexibly engage the shouldered part of the bulb as indicated in Figure 1.

It is believed that the manner of assembling the spacer members 39 and 48 in the disc 25, will be obvious from the foregoing description. With the arrangement as described, the electrode assembly is supported at its upper end, by the four downwardly projecting portions 4| and 42 of the spacer members and any vibrations of the bulb are taken up by the flexible portions 4| and 42.

There are thus provided means for flexibly supporting the upper end of the electrode unit against the inner wall of the bulb. As is customary, the electrode unit is previously assembled together with the stem 3 and press 4 to form a moun which is inserted within the bulb and suitably united thereto in any well known manner. Because of the particular design of the spacers as described, and their particular manner of mounting, the assembling of the mount within the bulb is relatively simple, and the spacers may be designed for use in tubes having domes of different internal diameters.

While the drawing shows the invention as embodied in a so-called dome type envelope, it

will be understood that it is capable of embodiment in any other known type of envelope. Furthermore, while the drawing shows two oppositely disposed spacers, a greater or less number may be employed if desired. Similarly, while the drawing shows the spacers attached to the upper disc 25, similar spacers may, if desired, be attached to the lower disc 26.

Where it is not desired to employ an interlocking arrangement between the disc and members 39, 49 the simplified arrangement as shown in Figs. 6 and '7 may be employed. In Fig. 6 only the disc 25 and the uprights H and I2 of the assembly of Fig. 4 are shown. The members 39 and 49 are replaced by mica strips or sheets 64 of the shape shown in Fig. 7. Each of these strips is formed with projections 82, 63 and a narrow neck portion around which is strapped a metallic strip 65, to general T-shape. The projecting end 69 of each strap is fastened, for example by spot Welding to the respective posts I l and [2, preferably at such an angle that the strips 64 rest against the edge of disc 25 as shown. The strips or spacers 64 are so designed that the projections 62, 63 alone engage the inner wall of the glass envelope 1, in a manner similar to that described in connection with members 39 and 49. Here again because of the inclined position of the members 64 only their lower ends engage the wall I and consequently any flexing of these members is effected around an axis which is at an angle to the vertical axis of the electrode assembly.

Instead of employing mica spacers, metallic wire spacers may be employed. Thus as shown in Figs. 8 and 9, the mica disc 19 which corresponds to disc 25 of Figs. 1 to 4, is provided at each end with a pair of aligned slits H and 12 through which is passed a flexible wire 13. The median portion of each wire is offset as at 14, so as to lie against the upper face of the disc between the slits. The free ends 15, 16 of each wire are bent downwardly at an angle so as to engage the wall of the envelope l in the manner shown in Fig. 9. Disc 10 may be fastened to the electrode unit in any suitable manner. For example the disc may be provided with metal eyelets 11 adapted to receive the upper ends of the plate support rods similar to rods II and I2 of Fig. 4, to which they may be welded or soldered. If desired, the tips of wires 13 where they engage the envelope, may be coated with heat insulating material such as glass, mica or the like. If desired, the free-ended wires 13 may be attached to one or more of the electrodes instead of being removaby interlocked with the mica disc 19 as shown.

Various changes and modifications may be made herein without departing fromv the spirit and scope of the invention. The subject matter disclosed herein and not claimed is claimed in oopending application Serial No. 129,993, filed March 10, 1937 and Serial No. 190,203, filed February 12, 1938.

What I claim is:

1. In combination, an enclosing envelope, an electrode assembly mounted within said envelope, a pair of separable interlocked insulator members carried by said assembly, one of said members having at least one downwardly extending free portion flexibly engaging the inner wall of said envelope.

2. In combination, an enclosing envelope, a

pair of interlocked members mounted within said envelope, one of said members having a yoke portion with spaced leg portions extending therefrom and interlocked to the other member so that only the said leg portions are in contact with the envelope.

3. In combination, an enclosing envelope, having a shoulder, an electrode assembly mounted within said envelope, a strip of flexible material carried by said assembly and inclined to the vertical axis of the envelope, and means supporting said strip in engagement with only the shoulder of said envelope.

4. The combination according to claim 3 in which said strip is provided with a yoke portion with spaced leg portions extending therefrom and only the leg portions are in contact with said shoulder of the envelope.

5. Spacer means for a radio tube or the like comprising a disc, a strip of flexible insulating material, said strip having a portion extending through said disc at substantially right angles thereto and interlocked therewith, and another portion inclined to said disc and interlocked therewith.

6. Spacer means for a radio tube or the like comprising a disc having a pair of aligned openings, and a third opening offset with respect to said pair of openings, and a strip of flexible material having a pair of projections interlocked with the edges of said pair of openings and another projection interlocked with the edge of said third opening.

7. Spacer means for a radio tube or the like comprising an insulator support, a pair of flexible members separably interlocked with said support, each of said members having a pair of projections extending beyond said support and inclined at an angle thereto.

8. Spacer means for a radio tube or the like comprising a strip of mica having a pair of projections, an insulator support and means including shouldered portions on said strip and slots in said support for separably interlocking said strip and support, said strip when interlocked having its projections inclined outwardly at an angle to said support.

9. Spacer means for a radio tube or the like comprising a support having a pair of aligned notches in the edge thereof, a slot in the body thereof, a mica strip having a pair of projections positioned in said notches, and a central lug positioned in said slot.

10. Spacer means according to claim 9 in which said slot is offset with respect to said notches, and said strip is provided with interlocking shoulders to prevent dislodgement thereof.

11. In combination, an enclosing envelope, an electrode unit extending along the vertical axis of said envelope, and a pair of flexible strips carried by said unit, said strips being mounted so that adjacent ends converge toward the said vertical axis and the opposite ends extend outwardly beyond said unit into flexible engagement with the wall of the envelope.

12. In combination, an enclosing envelope, an electrode unit mounted within said envelope, and a pair of mica members mounted at opposite sides of said unit, said members being inclined towards each other and having free ends engaging the envelope wall.

WALTER LOUIS KRAI-IL. 

